The self-calibration technology has been widely used in DAC. Generally, the self-calibration technology can be categorized into background calibration and foreground calibration. Background calibration means that the DAC stays at normal operations when an error is synchronously calibrated, while foreground calibration means that an error is calibrated before the DAC operates.
There are many reports disclosing methods for improving the linearity of a DAC, for example, U.S. Pat. No. 5,666,118 and U.S. Pat. No. 6,664,909. However, there are some problems in the aforesaid references that have to be overcome. U.S. Pat. No. 5,666,118 uses digital mechanism to trim the error for a DAC and stores the error of each cell of the DAC in the memory. However, the digital mechanism may be too complicated and consume a larger area and more power. U.S. Pat. No. 6,664,909 is an example utilizing the floating-gate synapse transistor to trim the current sources. The usage for the synapse transistor is inevitable for the DAC.
Accordingly, the present invention provides a self-calibrated device and an operation method thereof. More particularly, the present invention provides an analog self-calibrated method and device, capable of overcoming the problems such as large calibration circuit area, high power consumption or high manufacturing cost.